1. Field of the Invention
Following embodiments relate to a positron emission tomography (PET). A method and apparatus for processing a Monte-Carlo simulation in parallel using a graphics processing unit (GPU) for gamma-ray scatter estimation are disclosed.
2. Description of the Related Art
Tomography refers to an imaging method for non-invasively observing a specific cross section of an object without causing an overlap with another adjacent cross section by rotating a detector by about 180° or about 360°.
A sinogram refers to a plurality of images obtained through the tomography. The sinogram is reconstructed into a 3-dimensional (3D) image. An observer may observe a specific cross section of an imaged object through the reconstructed 3D image.
A tomographic image in nuclear medicine refers to an image expressing distribution characteristics of radioactive medicine given into an object person and distributed according to biochemical characteristics.
A level of radiation of the radioactive medicine to be given into a body is restricted in accordance with the corresponding standard. Therefore, a high-definition image may be difficult to be reconstructed from an observed value recorded by a small amount of photons.
When a tomogram is photographed using a nuclear medicine imaging device, while strength of an observed signal is low, a noise level may be relatively high.
Therefore, scattering of gamma rays may greatly affect an image reconstruction result. To compensate for an image noise induced by the gamma-ray scattering, an approximated gamma-ray scatter estimation algorithm such as single scattering simulation is widely used.
Monte-Carlo simulation generates a gamma-ray photon one by one and simulates of gamma-ray photon migrations to be similar to the real.
Monte-Carlo simulation may be the standard for researchers to predict and estimate feasible phenomena. However, Monte-Carlo simulation is seldom used in actual clinics since at least several hours to several days of operation time are required for Monte-Carlo simulation. For the same reason, estimation and correction of gamma-ray scattering using Monte-Carlo simulation is seldom used for researches.
Estimation of gamma-ray scattering and final reconstruction of a 3D image may take most of the entire operation time.
A parallel processing may be adopted to reduce the operation time. According to the parallel processing, works may be divided into the same types and operations are performed simultaneously by a plurality of computation cores.
A central processing unit (CPU) or graphics processing unit (GPU) equipped with a multicore may be used for the parallel processing. Specifically, the GPU may perform large-scale parallel processing by including hundreds to thousands of cores in general. The GPU may perform not only a graphic operation but also a mathematical operation.